Load cell



Oct. 1964 R. A. SCHULTZ 3,151,480

LOAD CELL Filed Aug. 10, 1960 INVENTOR ROBERT A. SCHULTZ Attorney UnitedStates Patent 3,151,480 LOAD CELL Rohert A. Schultz, Penn HillsTownship, Allegheny County, Pa., assignor to United States SteelCorporation, a corporation of New Eersey Filed Aug. 10, 1960, Scr. No.48,626 6 Claims. (Cl. 73-141) This invention relates to load cells and,in particular, to a cell of low height adapted for measurement oftensile or compressive loads.

Load cells have been constructed by the attachment of strain gages tomembers axially loaded as columns. The height of such cells is excessivefor many potential applications.

I have invented a load cell including a disc-like primary memberyieldable under pressure and a secondary member subjected to tension asa result of the yielding of the disc-like member under load. In apreferred embodiment, one or more dished washers, e.g.,Belleville-spring Washers, may serve as the primary member. A disc orstrap having a strain gage thereon is mounted therewith so as to bestressed in tension as a result of compression of the washers. Thiscombination affords a cell of minimum height.

A complete understanding of the invention may be obtained from thefollowing detailed description and explanation which refer to theaccompanying drawings illustrating the present preferred embodiment. Inthe drawmgs:

FIGURE 1 is a plan view;

FIGURE 2 is a section taken along the plane of line 11-11 of FIGURE 1;and

FIGURES 3 and 4 are plan views of modified secondary or tension members.

Referring now in detail to the drawings and, for the present,particularly to FIGURES 1 and 2, my improved cell comprises a pair ofdished or Belleville-spring washers or discs 11 disposed on oppositesides of a flat disc 12 of sheet metal. The disc has a thickenedmarginal ring 13 against the interior of which the peripheries ofwashers 11 abut closely. Strain gages 14 are alfixed to disc 12 inpositions such that they are alfected by dimensional changes in thedisc.

It will be evident that, on application of compressive force axially toWashers 11,. they will be slightly collapsed and, as a result, will tendto enlarge disc 12 radially. This dimensional change alters theresistance of gages 14 whereby a significant signal may be obtained,proportional to the load applied.

Instead of disc 12, the secondary or tension member 3,151,480 PatentedOct. 6, 1964 2 may be a ring 15, shown in FIGURE 3, having a diametralsheet strap 16 to which strain gages 14 are attached. As a furthermodification, the truncated ring 18 of FIGURE 4, may be utilized. It isgenerally similar to ring 15 but includes simply arcuate segments 19,one at each end of connecting strap 17.

It will be apparent that the cell of my invention has not only theadvantage of low overall height, but also of extreme simplicity and awide range. A slight compression of spring washers 11 is magnified asthe tension applied to disc 19 or to the strap 16 of ring 15. Easilyinterpreted signals are produced thereby.

Although I have disclosed herein the preferred embodiment of myinvention, I intend to cover as Well any change or modification thereinwhich may be made without departing from the spirit and scope of theinvention.

I claim:

1. A load cell comprising a dished disc and a sheet extending across theconcave face of said disc, means transmitting to said member the radialextension of said disc resulting from a compressive load applied axiallythereof, and a strain gage secured to said member.

2. A load cell comprising a pair of dished discs arranged in opposedrelation, a sheet member extending diametrally therebetween, said discsbeing disposed one on each side of said member with their concave facesadjacent thereto, means transmitting to said member the radial extensionof said discs resulting from a compressive load applied axially thereof,and a strain gage secured to said member.

3. A load cell as defined in claim 2, characterized by said member beinga ring with a diametral strap.

4. A load cell as defined in claim 2, characterized by said member beinga strap having arcuate segments at its ends.

5. A load cell as defined in claim 2, characterized by said member beinga disc.

6. A load cell as defined in claim 5, characterized by said member beinga fiat disc, said means being raised peripheral portions on said flatdisc engageable by the edges of said dished discs.

References Cited in the file of this patent UNITED STATES PATENTS1,875,524 Templin Sept. 6, 1932 2,636,964 Lancor et a1 Apr. 28, 19532,848,892 Hoilm-an Aug. 26, 1958 3,036,283 Singdale et a1 May 22, 1962FOREIGN PATENTS 1,025,170 Germany Feb. 27, 1958 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No, 3, 151L480 October 6 1964Robert A. Schultz ertified that error appears in the above numbered pat-Patent should read as It is hereby c nd that the said Letters entrequiring correction a corrected below.

Column 2, line 18 after "sheet" insert tension member Signed and sealedthis 30th day of March 1965,

(SEAL) Attest:

EDWARD J. BRENNER ERNEST W. SWIDER' Attesting Officer Commissioner ofPatents UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION PatentNo 3 151 48O October 6 1964 Robert A. Schultz ears in the above numberedpattified that error app Patent should read as It is hereby oer entrequiring correction and that the said Letters corrected below.

Column 2, line 18 after "sheet" insert tension member ned and sealedthis 30th day of March 1965;

Sig

(SEAL) Attest:

EDWARD J. BRENNER ERNEST W. SWIDER Attesting Officer Commissioner ofPatents

1. A LOAD CELL COMPRISING A DISHED DISC AND A SHEET EXTENDING ACROSS THECONCAVE FACE OF SAID DISC, MEANS TRANSMITTING TO SAID MEMBER THE RADIALEXTENSION OF SAID DISC RESULTING FROM A COMPRESSIVE LOAD APPLIED AXIALLYTHEREOF, AND A STRAIN GAGE SECURED TO SAID MEMBER.